WO2024031313A1

WO2024031313A1 - Electrode sheet, electrochemical apparatus, and electronic device

Info

Publication number: WO2024031313A1
Application number: PCT/CN2022/111078
Authority: WO
Inventors: 陈腾腾; 邓道林; 陈文�; 王冰
Original assignee: 宁德新能源科技有限公司
Priority date: 2022-08-09
Filing date: 2022-08-09
Publication date: 2024-02-15
Also published as: CN116848721A

Abstract

The present application discloses an electrode sheet, an electrochemical apparatus, and an electronic device. The electrode sheet comprises a current collector and a tab; the tab is connected to the current collector; chamfer portions are provided at end corners of the end of the tab facing away from the current collector. According to the present application, the chamfer portions are provided at the end corners of the end of the tab facing away from the current collector, so that the swing rigidity and the torsional rigidity of the tab can be improved, thereby suppressing the folding and inward insertion phenomena of tabs during winding of electrode sheets, and improving the production yield of electrochemical devices.

Description

Pole pieces, electrochemical devices and electronic equipment

Technical field

The present application relates to the field of battery technology, and in particular to a pole piece, an electrochemical device and an electronic device.

Background technique

Batteries with multi-lug structure pole pieces, because the pole pieces lead out tabs in the multiple winding layers of the battery core, greatly shorten the electronic conduction path, can greatly reduce the internal resistance of the battery, thus meeting the needs of mobile phones, laptops, Demand for high-magnification applications such as drones, power tools, electric vehicles, and electric two-wheelers.

Contents of the invention

However, the inventor of the present application has discovered through research that existing pole pieces with multi-pole tab structures are prone to tab folding and interpolation during the winding process, seriously affecting the production yield.

In view of this, the present application provides a pole piece, an electrochemical device and an electronic device, which can effectively improve the folding and interpolation phenomenon of the tab during the production process and improve the production efficiency of the electrochemical device.

In a first aspect, the present application provides a pole piece, including a current collector and a pole tab; the pole tab is connected to the current collector; and an end corner of the pole tab away from the current collector is provided with a chamfered portion. . By arranging a chamfered portion at the end corner of the end of the tab away from the current collector, the swing stiffness and torsional stiffness of the tab can be improved, thus suppressing the tab from being folded or interpolated during the winding process of the pole piece, and improving the electrical power. Production excellence rate of chemical plants.

In some embodiments, chamfered portions are provided at both end corners of the end of the pole tab away from the current collector. Cut corners are provided at both end corners, which is beneficial to improving the swing stiffness and torsional stiffness on both sides of the tab, and further suppresses the phenomenon of folding and interpolation of the tab during the winding process of the pole piece.

In some embodiments, the outer edge of the chamfered portion is independently selected from any one of a straight line, an outer convex arc, or an inner concave arc.

In some embodiments, the tab is formed by an extension of the current collector. At this time, on the one hand, the connection strength between the tab and the current collector can be improved and the risk of the tab falling off can be reduced; on the other hand, the manufacturing of the tab can be greatly simplified and the processing efficiency can be improved.

In some embodiments, the pole piece includes a plurality of the tabs. The pole piece includes a plurality of the pole tabs, which can greatly improve the rate performance of the electrochemical device, thereby better meeting the needs of high-rate applications.

In some embodiments, the outer edge of the chamfered portion has a first endpoint and a second endpoint; the tab is provided with a first side and a bottom side connected to the current collector, and the first side One end of the side is connected to the bottom side, and the other end of the first side is connected to the first endpoint; the angle between the first side and the bottom side is α, and the first end The angle between the line connecting the point and the second endpoint and the first side is λ, β=λ-(180°-α), and satisfies: β<α. By satisfying β<α, the swing stiffness and torsional stiffness of the tip at the end can be improved, thereby suppressing the tip folding and interpolation during the winding process of the pole piece, and improving the production efficiency of the electrochemical device.

In some embodiments, α-β≥9°. In some embodiments, α-β≥15°. At this time, the swing and twist of the pole tab at the end can be further restricted, thereby further suppressing the phenomenon of folding and interpolation of the pole tab during the winding process of the pole piece.

In some embodiments, 0°<α≤90°. In some embodiments, 40°≤α≤86°. At this time, the first side and the bottom edge are set at an acute angle, and the width of the pole gradually narrows in the direction away from the current collector, which can further increase the swing stiffness and torsional stiffness of the pole at the end, thereby further suppressing the polarity. The ears appear to be folded and interpolated during the winding process of the pole piece.

In some embodiments, α-β≤75°.

In some embodiments, the bottom edge width of the pole tab is L, the height of the pole tab is H, and the top edge width of the pole tab is 2l; wherein, the width direction of the pole tab is in the same direction as the collector. The length direction of the fluid is parallel, and the height direction of the pole tab is perpendicular to the length direction of the current collector, satisfying: 0≤l≤0.8(L/2-H/tanα).

In some embodiments, it is satisfied: 0≤l≤0.4(L/2-H/tanα). At this time, the swing and twist of the pole tab at the end can be further restricted, thereby further suppressing the phenomenon of folding and interpolation of the pole tab during the winding process of the pole piece.

In some embodiments, the length of the first side is h, which satisfies: 0.2H/sinα≤h≤0.8H/sinα.

In some embodiments, it is satisfied: 0.3H/sinα≤h≤0.7H/sinα. At this time, the swing and twist of the pole tab at the end can be further restricted, thereby further suppressing the phenomenon of folding and interpolation of the pole tab during the winding process of the pole piece.

In a second aspect, this application also provides a method for preparing an electric core, including the step of winding the pole piece described in any one of the above.

In a third aspect, the present application also provides an electrochemical device, including the pole piece described in any one of the above or the electric core prepared by the above preparation method.

In a fourth aspect, the present application also provides an electronic device, including the electrochemical device described in any one of the above.

This application can improve the swing stiffness and torsional stiffness of the pole tab by arranging a chamfered portion at the end corner of the pole tab away from the current collector. The number of pole tab folds during the winding process of the pole piece described in this application Significantly reduced, the corresponding rate of cell production failure is also significantly reduced; therefore, it can effectively improve the folding and interpolation phenomenon of the tabs during the pole piece winding process, and improve the production efficiency of electrochemical devices.

Description of drawings

In order to explain the embodiments of the present application or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only These are some embodiments of the present application. For those skilled in the art, other drawings can also be obtained based on these drawings.

Figure 1 is a schematic diagram of the tab structure (base tab) of the prior art;

Figure 2 is a schematic structural diagram of the cut-angle tab described in this application;

Figure 3 is a schematic structural diagram of a straight-line angle cutter in the embodiment of the present application;

Figure 4 is a schematic structural diagram of the angle-cut pole tab in the embodiment of the present application, which is a concave arc-shaped angle;

Figure 5 is a schematic structural diagram of the angle-cut pole in the embodiment of the present application, which is an external convex arc-shaped angle;

Figure 6 is a schematic diagram of parameters in which the angle-cut tab is a straight-line angle cutter in the embodiment of the present application;

Figure 7 is a schematic diagram of specific parameters of the angle-cut tab in the embodiment of the present application;

Figure 8 is a picture of the modal analysis results of the tab structure (base tab) of the prior art.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present application more clear, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present application and are not used to limit the present application.

Please refer to Figure 1 , which shows a base tab structure in the prior art. It is usually an isosceles trapezoid tab, that is, the outer contour of the tab is an isosceles trapezoid structure.

The inventor of this application has found that during the winding process of the pole piece, the existing base tab is prone to folding and interpolation. Especially for batteries with multi-lug structure pole pieces, there are many poles in the battery core. For pole pieces with tab structures, the probability of tab folding and interpolation during the winding process is greatly increased, seriously affecting the production efficiency.

In view of this, this application proposes a pole piece, an electrochemical device and an electronic device to improve or at least partially solve the above technical problems.

a pole piece

Please refer to Figure 2. The pole piece includes: a current collector 1 and a pole tab 2 (sometimes also called a cut-angle tab in the text); the pole tab 2 is connected to the current collector 1; specifically, the pole tab 2 The end of one side close to the current collector 1 is connected to the current collector 1. The connection can be integrally formed, bonded, welded or other fixed methods, as long as the tab 2 and the current collector can be realized. 1 only needs to be fixedly connected, and this application is not limited to this. Specifically, in some examples, the pole tab 2 is formed by extending the current collector 1. At this time, the pole tab 2 and the current collector 1 1 is formed in one piece. During the pole piece cutting process, the corresponding pole tab 2 can be obtained by cutting the empty foil area on the edge of the current collector 1, which greatly simplifies the manufacturing of pole tab 2 and improves the processing efficiency; A corner cutout 21 is provided at an end corner of the other end of the pole tab 2 away from the current collector 1 . By arranging the chamfered portion 21 at one end corner or both end corners of the end of the pole tab 2 away from the current collector 1 (ie, the outer end of the pole tab 2 ), the pole tab 2 can be lifted. The swing stiffness and torsional stiffness are thereby suppressed from the phenomenon of folding and interpolation of the pole tab 2 during the winding process of the pole piece.

Optionally, in some examples, one end corner of the outer end of the pole lug 2 is provided with the chamfered portion 21; or in other examples, both sides of the outer end of the pole lug 2 are The end corners are provided with the chamfered portions 21 .

Please refer to Figures 3 to 5. In some examples, chamfered portions 21 are provided at both corners of the end of the pole tab 2 away from the current collector 1; the two chamfered portions 21 are provided on the The end corners of the outer ends of the pole tabs 2 are centrally symmetrical, which is beneficial to improving the swing stiffness and torsional stiffness on both sides of the pole tabs 2 and further inhibiting the pole tabs 2 from folding or folding during the winding process of the pole pieces. interpolation phenomenon. In some examples, the outer edge 211 of the chamfered portion 21 is independently selected from any one of a straight line, an outer convex arc, or an inner concave arc.

Optionally, in some examples, the chamfered portion 21 is provided at an end corner of the end of the pole lug 2 away from the current collector 1 , and the outer edge 211 of the chamfered portion 21 may be a straight line. , it may be an outer convex arc, or it may be an inner concave arc; preferably, the outer edge 211 of the chamfered portion 21 is an inner concave arc. In other examples, chamfered portions 21 are provided at both end corners of the end of the pole lug 2 away from the current collector 1 , and the outer edges 211 of the two chamfered portions 21 are the same. It is a straight line, a convex arc, or a concave arc; preferably, the outer edges 211 of the two chamfered portions 21 are both concave arcs. And in other examples, chamfered portions 21 are provided at both end corners of the end of the pole lug 2 away from the current collector 1 , and the outer edges 211 of the two chamfered portions 21 are different. The outer edge 211 of one of the chamfered portions 21 is a straight line, and the outer edge 211 of the other chamfered portion 21 is a convex arc or a concave arc.

As shown in FIG. 3 , chamfered portions 21 are provided at both corners of the outer end of the pole lug 2 , and the outer edges 211 of the two chamfered portions 21 are both straight and centrally symmetrical. , at this time, it can be said that the two end corners of the outer end of the pole tab 2 are provided with straight-line chamfers.

As shown in Figure 4, the two corners of the outer end of the pole lug 2 are provided with chamfered portions 21, and the outer edges 211 of the two chamfered portions 21 are both concave arcs and are in the shape of a concave arc. The pole tab 2 is arranged symmetrically at the center. At this time, it can be said that the two end corners of the outer end of the pole tab 2 are provided with concave arc-cut corners.

As shown in FIG. 5 , chamfered portions 21 are provided at both corners of the outer end of the pole lug 2 , and the outer edges 211 of the two chamfered portions 21 are both convex arcs. The pole tab 2 is arranged symmetrically at the center. At this time, it can be said that the two end corners of the outer end of the pole tab 2 are provided with convex arc-cut corners.

Referring to Figure 6, the outer edge 211 of the chamfered portion 21 has a first endpoint and a second endpoint; the pole tab 2 is provided with a first side and a bottom edge connected to the current collector 1. One end of the first side is connected to the bottom edge, and the other end of the first side is connected to the first endpoint; the angle between the first side and the bottom edge is α (slope angle ), the angle between the line connecting the first endpoint and the second endpoint and the first side is λ, β=λ-(180°-α), satisfying: β<α. By limiting the angle β between the line connecting the first endpoint and the second endpoint of the chamfered portion 21 and the horizontal line to satisfy: β<α, the pole lug 2 can be raised to the outer end. The swing stiffness and torsional stiffness are thereby suppressed from the phenomenon of folding and interpolation of the pole tab 2 during the winding process of the pole piece; the horizontal line is a straight line parallel to the bottom edge.

Optionally, in some examples, the pole piece satisfies α-β≥9°. By satisfying α-β≥9°, the swing stiffness and torsional stiffness of the pole tab 2 at the outer end can be improved, thereby further suppressing the phenomenon of folding and interpolation of the pole tab 2 during the pole piece winding process. Illustratively, the α and β differences (α-β) are 9°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65° , 70°, 75°, 80° or a range consisting of any two of the above values. Optionally, in some examples, the pole piece satisfies α-β≥15°; at this time, the swing and torsion of the pole tab 2 at the outer end can be further restricted, thereby further suppressing the movement of the pole tab 2 at the pole piece. Folding and interpolation phenomena occur during the winding process. In other examples, the pole piece satisfies α-β≤75°.

In some examples, the pole piece satisfies 0°<α≤90°. For example, the value range of α is 10°, 20°, 40°, 60°, 80°, 86°, 90° or a range consisting of any two of the above values. In some examples, the pole piece satisfies 40°≤α≤86°; at this time, the first side and the bottom edge are set at an acute angle, and the width of the pole piece gradually narrows in the direction away from the current collector, which can further The swing stiffness of the pole tab 2 at the outer end is increased, thereby further suppressing the phenomenon of folding and interpolation of the pole tab 2 during the winding process of the pole piece.

Referring to Figure 6, the bottom width of the pole tab 2 is L, the height of the pole tab 2 is H, and the top edge width of the pole tab 2 is 2l, which satisfies: 0≤l≤0.8(L/2- H/tanα); wherein, the width direction of the pole tab 2 is parallel to the length direction of the current collector 1 , and the height direction of the pole tab 2 is perpendicular to the length direction of the current collector 1 . Among them, (L/2-H/tanα) is the top half width of the base tab, and (L/2-H/tanα) is recorded as parameter B. When cutting the tab, it is equivalent to cutting the top edge of the base tab. The edge width is cut. The top half-width l of the pole tab 2 ranges from 0 to 0.8B, that is, relative to the top half-width of the base tab, the cut length is B-l (i.e., the top half-width in Figure 6 The extension line of one end of the side half-width l extends to the distance when it intersects the extension line of the first side h).

Illustratively, the half-width l of the top edge of the pole lug 2 is 0, 0.01B, 0.1B, 0.15B, 0.2B, 0.25B, 0.3B, 0.35B, 0.4B, 0.6B, 0.8B or any of the above A range of two values.

Preferably, the half-width l of the top edge of the pole lug 2 satisfies: 0≤l≤0.4(L/2-H/tanα); that is, l satisfies: 0≤l≤0.4B. At this time, the swing and twist of the pole tab 2 at the outer end can be further restricted, thereby further suppressing the phenomenon of folding and interpolation of the pole tab 2 during the winding process of the pole piece.

Moreover, with reference to Figure 6, the length of the first side is h, which satisfies: 0.2H/sinα≤h≤0.8H/sinα. Wherein, H/sinα is the length of the hypotenuse of the base tab, one end of the hypotenuse of the base tab is connected to its top edge, and the other end of the hypotenuse of the base tab is connected to its bottom edge. Record (H/sinα) as parameter A. When cutting the tab, it is equivalent to cutting the hypotenuse of the base tab. The length of the first side of the tab 2 ranges from 0.2A to 0.8A. That is, the actual cut length of the hypotenuse of the base tab is A-h (that is, the distance when the extension line of the first side h in Figure 6 extends to intersects the extension line of the top half-width l).

For example, the length h of the first side is a range of 0.2A, 0.3A, 0.4A, 0.5A, 0.6A, 0.7A, 0.8A or any two of the above values.

Preferably, the length h of the first side satisfies: 0.3H/sinα≤h≤0.7H/sinα; that is, h satisfies: 0.3A≤h≤0.7A. At this time, the swing and twist of the pole tab 2 at the outer end can be further restricted, thereby further suppressing the phenomenon of folding and interpolation of the pole tab 2 during the winding process of the pole piece.

In some examples, the pole piece is a positive pole piece. In some examples, the pole piece is a negative pole piece.

In some examples, the pole piece further includes an active material layer located on the surface of the current collector. In some examples, the active material layer is a positive active material layer, and the positive active material layer includes a positive active material. In some examples, the active material layer is a negative active material layer, and the negative active material layer includes a negative active material.

an electrochemical device

The electrochemical device includes an electric core, and the electric core includes any of the above-mentioned pole pieces of the present application. The electric core can be prepared according to conventional methods in the art. Specifically, the preparation of the electric core includes the step of winding any one of the above pole pieces.

The electrochemical device of the present application may include any device that undergoes an electrochemical reaction, for example, it may be a lithium-ion battery, a sodium-ion battery, etc.; specific examples thereof include all kinds of primary batteries or secondary batteries. In particular, the electrochemical device is a lithium secondary battery, including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery or a lithium ion polymer secondary battery.

an electronic device

The electronic device includes any one of the above electrochemical devices of the present application. The electronic device of the present application can be used in, but not limited to, notebook computers, pen input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, stereo headsets, video recorders, LCD TV, portable cleaner, portable CD player, mini CD, transceiver, electronic notepad, calculator, memory card, portable recorder, radio, backup power supply, motor, automobile, motorcycle, power-assisted bicycle, bicycle, lighting equipment , toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries and lithium-ion capacitors, etc.

Hereinafter, embodiments of the present application will be described in more detail with reference to Examples and Comparative Examples.

Taking multi-lug large soft-pack batteries as an example to compare the effect of improving production efficiency, the quantity is 200, and the wound battery core in a large soft-pack battery has 108 die-cut tabs. Count the number of discounted wound batteries.

The height of the base tab for this verification is H = 24mm, the bottom width L = 35mm, the slope angle α = 86°, the side length (parameter A) is calculated to be 24.06mm, and the top edge width (parameter B) is calculated to be 24.06mm. The result is 15.8mm, and the corresponding experimental results are shown in Table 2.

The parameters after chamfering the two end angles at the outer end of the base tab are shown in Table 2. The outer edge of the corner-cut portion can be a straight line, a convex arc, or a concave arc. In Embodiment 1, the straight-line corner-cut tab has a β angle of 45°, and the first side length h is 15 mm. The half-width l of the top edge is 7.45mm; in Example 2-3, the outer convex arc cut angle and the inner concave arc cut angle are obtained according to the change of the straight line cut angle, that is, the positions of the hypotenuse and the top edge are consistent with the straight line cut angle. The vertical distance from the maximum point of curvature radius in convex arc lines and concave arc lines to the straight line tangent angle is 2.5mm; the corresponding dimensions are shown in Figure 7; the test data are shown in Table 1 below:

Table 1

It can be seen from the parameter characteristics and test results in Table 1 that compared with Comparative Example 1, Examples 1 to 3 were respectively cut on the base tab to obtain a corner portion. Among them, the corner portion after cutting in Example 1 The outer edge of the part is a straight line, that is, a straight-line cut angle is obtained. The number of tabs folded during the test of 200 cells with straight cut-angle tabs is 2, and the corresponding cell production failure rate is 1%; Example 2 The outer edge of the cut corner after cutting is a convex arc, that is, the convex arc cut corner is obtained. The number of tabs folded during the test of 200 cells with convex arc cut corners was 4 , the corresponding cell production failure rate is 2%; the outer edge of the cut corner in Example 3 is a concave arc, that is, a concave arc cut corner is obtained, and 200 concave arc cut corners are obtained. The number of battery cells that had tabs folded during the test was 1, and the corresponding battery cell production failure rate was 0.5%. It can be seen that the swing and torsional stiffness of the concave arc-shaped tab has the best improvement effect, and its corresponding cell production failure rate is only 0.5%, which is much lower than the 6% cell production failure rate of the base tab.

From the comparison between Examples 4 to 8 and Example 9, it can be seen that the half width l of the top edge of the cut-angle tab is controlled between 0 and 0.8B, that is, 0≤l≤0.8(L/2-H/tanα), The strength of the obtained cut-angle tab is better than that of the cut-angle tab that is not in this range, that is, the half-width l of the top edge is in the range of 0 to 0.8B, and its folding limiting effect is better. For example, the value of l in Example 9 is 0.9 (L/2-H/tanα), and the number of tab folds in 200 cells during the test is 7, which is much higher than that in Examples 4 to 8. Quantity, the number of folds in Examples 4 to 8 is less than or equal to 3, and the minimum can be 1; the battery cell production failure rate corresponding to Example 9 is 3.5%, and the battery cell production failure rate corresponding to Examples 4 to 8 does not exceed 1.5%; Moreover, comparing Examples 4 to 6 with Examples 7 to 8, Examples 4 to 6 control the half width l of the top edge of the cut-angle tab to 0 to 0.4B, that is, 0 ≤ l ≤ 0.4 ( L/2-H/tanα), which has a better effect of limiting folding, and the corresponding cell production failure rate is also lower.

From the comparison between Examples 11 to 15 and Examples 10 and 16, it can be seen that the length of the first side h of the cut-angle tab is controlled to 0.2A to 0.8A, that is, 0.2H/sinα≤h≤0.8H/ sinα, the swing and torsion strength of the cut-angle pole obtained is better than the swing and torsion strength of the cut-angle pole that is not in this range, that is, the length of the first side h is in the range of 0.2A ~ 0.8A, which limits the folding The effect is better. For example, the values of the first side h in Example 10 and Example 16 are 0.1A and 0.9A respectively. The number of tabs that occurred in the 200 cells during the test was 6, which is much higher than that in the Example. The number of folds of 11 to 15, the number of folds of Examples 11 to 15 is less than or equal to 4, and the minimum can reach 1; and the battery core production failure rate of Examples 10 and 16 is 3%, while the failure rate of Examples 11 to 15 The corresponding cell production failure rate does not exceed 2%; moreover, comparing Examples 12 to 14 with Examples 11 and 15, Examples 12 to 14 control the first side h at 0.3A to 0.7A, that is, 0.3 H/sinα≤h≤0.7H/sinα has a better effect of limiting folding, and the corresponding cell production failure rate is also lower.

Comparing Example 9 with other examples, when α-β≥15° and α-β≤75° is satisfied, the number of tabs folded during the production of the battery core is significantly reduced, and the failure rate of the battery core production is reduced. The improvement effect is significant.

Furthermore, in order to compare the stiffness, this application uses modal analysis for quantification. In the modal analysis, the first-order eigenfrequency corresponds to the swing stiffness, and the second-order eigenfrequency corresponds to the torsional stiffness (as shown in Figure 8); Table 2 below is Comparative Example 1 Modal analysis comparison results of the base tab and the cut-angle tab described in Example 1 of this application:

Table 2

组别Group	一阶特征频率first-order eigenfrequency	二阶特征频率second-order eigenfrequency
Base极耳Base tab	5.855.85	7.647.64
切角极耳chamfered tabs	6.216.21	9.139.13

It can be seen that the first-order characteristic frequency and the second-order characteristic frequency of the cut-angle tab in Embodiment 1 of the present application are greatly improved. The higher the first-order frequency, the less likely it is to swing up and down, and the higher the second-order frequency, the less likely it is to swing up and down. It is not easy to swing left and right angles; it can be seen that the swing and torsional stiffness of the angle-cut pole tabs are improved, which can suppress the folding and interpolation of the pole tabs during the pole piece winding process.

In the drawings of this embodiment, the same or similar numbers correspond to the same or similar components; in the description of this application, it should be understood that if there are terms such as "upper", "lower", "left", "right", etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation or a specific orientation. Construction and operation, therefore the terms describing the positional relationships in the drawings are only for illustrative purposes and cannot be understood as limitations of the patent. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the protection of the present application. within the range.

Claims

A pole piece includes: a current collector and a pole tab; the pole tab is connected to the current collector; and it is characterized in that an end corner of the pole tab away from the current collector is provided with a chamfered portion.
The pole piece according to claim 1, characterized in that the pole piece meets at least one of the following conditions:

(1) The two end corners of the end of the pole tab away from the current collector are provided with cut corners;

(2) The outer edge of the chamfered portion is independently selected from any one of straight lines, convex arcs, or concave arcs;

(3) The pole tab is formed by extending from the current collector;

(4) The pole piece includes a plurality of pole tabs.
The pole piece according to claim 1, wherein the outer edge of the chamfered portion has a first endpoint and a second endpoint;

The pole tab is provided with a first side and a bottom connected to the current collector, one end of the first side is connected to the bottom, and the other end of the first side is connected to the first endpoint connection;

The angle between the first side and the bottom is α, the angle between the line connecting the first endpoint and the second endpoint and the first side is λ, β=λ-( 180°-α), satisfying: β<α.
The pole piece according to claim 3, characterized in that the pole piece meets at least one of the following conditions:

(1)α-β≥9°;

(2)0°<α≤90°.
The pole piece according to claim 4, characterized in that the pole piece meets at least one of the following conditions:

(1)α-β≥15°;

(2)α-β≤75°;

(3)40°≤α≤86°.
The pole piece according to claim 3, characterized in that the bottom edge width of the pole tab is L, the height of the pole tab is H, the top edge width of the pole tab is 2l, and the first side The length of the side is h, where the width direction of the pole tab is parallel to the length direction of the current collector, the height direction of the pole tab is perpendicular to the length direction of the current collector, and the pole piece satisfies the following conditions: At least one of:

(1)0≤l≤0.8(L/2-H/tanα);

(2)0.2H/sinα≤h≤0.8H/sinα.
The pole piece according to claim 6, characterized in that the pole piece meets at least one of the following conditions:

(1)0≤l≤0.4(L/2-H/tanα);

(2)0.3H/sinα≤h≤0.7H/sinα.
A method for preparing an electric core, characterized in that it includes the step of winding the pole piece according to any one of claims 1 to 7.
An electrochemical device, characterized by comprising the pole piece according to any one of claims 1 to 7 or an electric core prepared according to the preparation method according to claim 8.
An electronic device, characterized by comprising the electrochemical device according to claim 9.